[Cheezeninja]

Penny-Arcade has a pretty active forum full of gamers, most of the comics tend to be game related as well, all it would probably take is one person properly posting and maintaining a thread to get a community going there. If it got popular enough for a front page article/comic there would be some serious traffic from it, given the number of hits the comic gets.

We've got a small to medium Dom3 community going in a thread on the Something Awful forums as well, usually with 2-3 games running concurrently. All it takes is one person enthusiastic enough to get the ball rolling.